AGRICULTURAL  INVESTIGATIONS 


BERT 


1  684 


UNIV.   OF    CAL, 
EKPT,   STA.  LIB, 


AGRIC,  DEPT, 


'/itb  the  compliments  of  HOUGHTON  FARM. 


r      ^  1  *          i 


ON 


AGRICULTURAL  INVESTIGATION- 


BEING 


A  LECTURE  DELIVERED  OCTOBER  27,  1884, 


AT 


RUTGERS  COLLEGE,  NEW  BRUNSWICK,  N.J 


UNDER    THE    AUSPICES    OF 


THE  NEW  JERSEY  AGRICULTURAL  EXPERIMENT  STATION, 

THE    STATE    BOARD   OF    AGRICULTURE,  AND 

THE  STATE  AGRICULTURAL  COLLEGE; 


JOHN  HENRY  GILBERT,  M.A.,  LL.D.,  F.R.S. 

OF    ROTHAMSTED,   ENGLAND. 

AND  SIBTHORPIAN  PROFESSOR  OF  RURAL  ECONOMY 
IN  THE  UNIVERSITY  OF  OXFORD. 


,\ 


PUBLISHED    BY    THE 

SOCIETY  FOR  THE  PROMOTION  OF  AGRICULTURAL  SCIENCE. 

1885. 


ON 


AGRICULTURAL  INVESTIGATION; 


BEING 


A  LECTURE  DELIVERED  OCTOBER  27,  1884, 


RUTGERS  COLLEGE,  NEW  BRUNSWICK,  N.  J 


UNDER    THE    AUSPICES    OF 


THE  NEW  JERSEY  AGRICULTURAL  EXPERIMENT  STATION, 

THE    STATE    BOARD    OF    AGRICULTURE,  AND 

THE  STATE  AGRICULTURAL  COLLEGE; 


JOHN  HENRY  GILBERT,  M.A.,  LL.D.,  F.R.S 

OF   ROTHAMSTED,   ENGLAND. 

AND  S1BTHORPIAN  PROFESSOR  OF  RURAL  ECONOMY 
IN  THE  UNIVERSITY  OF  OXFORD. 


PUBLISHED    BY    THE 

SOCIETY  FOR  THE  PROMOTION  OF  AGRICULTURAL  SCIENCE. 

1885. 


NOTE   ON   DR.    GILBERT  S   LECTURE. 

It  has  been  announced  that  Sir  John  Bennet  Lawes,  in  arranging  for  the  perpetual 
maintenance  of  the  great  work  of  Rothamsted,  makes  provision  for  a  representative 
of  that  establishment  to  visit- America  every  other  year  and  lecture  at  appropriate 
places. 

Dr.  Gilbert  was  in  the  United  States  in  1882,  and  when  it  was  known  that  he  was 
to  come  again  in  1884,  efforts  were  made  to  have  him  attend  the  fifth  annual  meeting 
of  the  Society  for  the  Promotion  of  Agricultural  Science.  As  his  various  engagements 
unfortunately  prevented  his  being  in  Philadelphia  at  the  time  desired,  arrangements 
were  there  made  to  secure  lectures  from  him  at  other  places.  He  accordingly  visited 
Lansing,  Michigan,  and  New  Brunswick,  New  Jersey,  for  the  purpose,  and  found 
appreciative  audiences  at  both  places. 

The  lecture  at  Rutgers  College  was  under  the  joint  auspices  of  the  New  Jersey 
Agricultural  Experiment  Station,  State  Agricultural  College,  and  State  Board  of 
Agriculture. 

,  The  Society  for  the  Promotion  of  Agricultural  Science,  having  intended  this 
lecture  to  be  a  part  of  its  proceedings  at  Philadelphia,  have  asked  and  obtained  per- 
mission to  first  publish  the  same  in  this  pamphlet.  For  this  purpose  the  text  has 
been  carefully  revised  and  the  tables  verified  by  Dr.  Gilbert.  This  kind  attention 
is  gratefully  acknowledged  by 

THE  EXECUTIVE  COMMITTEE. 


v  :  >': 


LECTURE  ON  AGRICULTURAL  INVESTIGATIONS. 

J.   H.  GILBERT. 


Mr.  President,  Professors  and  Students  of  Jtutgers  College, 

and  Ladies  and  Gentlemen  : 

I  ESTEEM  it  a  high  honor  and  a  great  responsibility  to  be  called 
upon  to  address  you  on  the  present  occasion; — an  honor  because, 
perhaps,  I  am  not  assuming  too  much  in  supposing  that  I  owe  the  invi- 
tation to  do  so  to  the  fact  that  the  joint  labors  of  Sir  John  Bennet  Lawes 
and  myself,  in  the  furtherance  of  agricultural  progress,  which  have  now 
extended  over  a  period  of  more  than  forty-one  years,  are  held  in  some 
appreciation  in  this  country;  —  and  a  responsibility,  because  I  know 
that  I  have  before  me  representatives  of  the  best  agricultural  science  in 
the  Eastern  States. 

On  hearing  from  Sir  John  Lawes,  before  leaving  home,  that  I  might 
probably  be  asked  to  lecture  at  some  Agricultural  Institutions  in  Amer- 
ica, I  at  once  decided  that  it  would  be  inappropriate  for  me  to  attempt 
to  discuss,  in  any  detail,  American  agricultural  practices  or  experiments ; 
that  in  these  matters  I  should  be  a  learner  rather  than  a  teacher ;  and 
that  it  would  be  more  suitable  for  me  to  give  some  account  of  the  results 
obtained  at  Rothamsted,  leaving  my  audience  to  decide  for  themselves, 
in  great  measure,  how  far  the  facts  and  the  conclusions  were  applicable 
to  American  conditions. 

In  Germany  and  France  very  much  good  work  has  been  done,  both 
in  the  laboratory  and  feeding-shed,  during  the  last  thirty  years  or  more ; 
but  in  Germany,  at  any  rate,  we  have  it  on  the  authority  of  Prof. 
Maercker  of  Halle,  one  of  their  leading  agricultural  chemists,  that  sys- 
tematic field  experiments  are  almost  abandoned  in  that  country.  In 
1880,  Prof.  Maercker  stated  that  belief  in  their  value  was  greatly  dimin- 
ished, and  that  by  some  they  were  declared  to  be  of  no  value.  It  was 
objected  that  the  chemists  of  the  Agricultural  Stations  have  neither  the 
means  nor  the  technical  knowledge  necessary  for  carrying  out  such 
experiments  successfully ;  that  neither  the  amount  of  land  nor  the  funds 
at  their  disposal  were  such  as  to  admit  of  any  safe  deductions  for  appli- 
cation in  practical  agriculture  from  the  results  ;  and  that  purely  physio- 
logical problems  could  be  better  investigated  in  the  laboratory  or  in  the 
greenhouse.  He  remarked  that,  owing  to  the  errors  necessarily  incident 
to  field  experiments  conducted  by  those  not  acquainted  with  practical 
agriculture,  the  confidence  of  the  practical  farmer  in  the  results  has  been 
shaken.  Indeed,  owing  to  the  difficulties  and  the  cost  of  such  inquiries, 


320923 


if  conducted  viiv  a  truly  'scientific  manner,  so  as  to  be  applicable  for  the 
solution  of  questions  of  fundamental  and  general  interest,  Prof.  Msercker 
concluded  that  the  only  field  experiments  which  it  was  practicable  to 
carry  out  in  Germany  were  such  as  should  be  conducted  by  the  practical 
farmer  himself,  to  test  the  applicability  to  practice,  of  results  and  conclu- 
sions otherwise  arrived  at ;  and  that,  to  insure  that  even  such  experi- 
ments should  not  be  misleading,  similar  ones  should  be  conducted  on 
different  descriptions  of  soil,  and  for  several  years  in  succession. 

That  the  great  cost  of  scientifically  conducted  field  experiments  should 
have  prevented  the  more  extended  prosecution  of  them,  is  perhaps  not 
surprising  when  I  tell  you  that  the  Rothamsted  field  experiments,  inde- 
pendently of  all  the  laboratory  investigations  connected  with  them,  cost 
considerably  more  than  ^1000  annually ;  whilst  those  which  have  been 
undertaken  by  the  Duke  of  Bedford  at  Woburn  for  the  past  seven  years, 
on  behalf  of  the  Royal  Agricultural  Society  of  England,  and  which  are 
under  the  direction  of  Dr.  Vcelcker,  cost  not  much  less  than  this. 

At  various  institutions  in  America,  and  preeminently  at  the  New 
Jersey  Agricultural  Experiment  Station,  very  much  good  work  is  being 
done  of  the  character  prosecuted  with  so  much  success  in  Germany,  and 
recommended  by  Prof.  Msercker  to  be  still  further  followed  up ;  and 
whilst  such  work  should  be  continued  and  extended,  surely  investiga- 
tions of  a  more  permanent  value,  and  of  more  general  application, 
should  not  be  neglected.  Nor  can  it  be  supposed  that  in  so  wealthy  a 
country  as  America,  where  there  is  so  much  munificence  and  public 
spirit  displayed  in  all  matters  of  progress,  the  cost  of  scientifically  con- 
ducted agricultural  experiments  will  be  any  obstacle. 

This  brings  me  to  the  special  subject-matter  of  my  lecture,  which  is  to 
illustrate  the  value  of  long  continued  and  carefully  conducted  experiments, 
by  reference  to  the  results  of  one  series  of  such  experiments  conducted 
at  Rothamsted, — namely,  those  on  the  growth  of  wheat  for  more  than 
forty  years  in  succession  on  the  same  land  —  ^vithout  manure,  with  farm- 
yard manure,  and  with  a  great  variety  of  chemical  manures. 

But,  before  entering  upon  the  details  of  this  subject,  it  will  be  well  to 
give  some  account  of  the  scope  and  plan  of  the  whole  investigation,  of 
which  these  special  results  only  form  a  part. 

At  Rothamsted,  no  questions  of  mere  local  interest  or  economy  are 
undertaken.  The  object  is  rather  to  investigate  the  principles  under- 
lying fundamental  practices  ;  and  whilst  results  obtained  in  one  locality, 
on  one  description  of  soil,  and  with  one  character  of  climate,  require  to 
be  carefully  studied  before  conclusions  applicable  to  other  localities  and 
to  other  countries  can  be  drawn,  yet  it  is  believed  that  the  results  which 
have  been  obtained  are  of  very  general  and  wide  application. 

The  general  scope  and  plan  of  the  field  experiments  has  been  —  to 
grow  some  of  the  most  important  crops  of  rotation,  each  separately,  year 
after  year,  for  many  years  in  succession  on  the  same  land,  without  ma- 
nure, with  farm-yard  manure,  and  with  a  great  variety  of  chemical  ma- 
nures, the  same  description  of  manure  being,  as  a  rule,  applied  year  after 
year  on  the  same  plot.  Experiments  with  different  manures  on  the 
mixed  herbage  of  permanent  grass-land,  on  the  effects  of  fallow,  and 
on  an  actual  course  of  rotation,  without  manure,  and  with  different 
manures,  have  likewise  been  made.  Field  experiments  have  thus  been 
conducted  for  the  periods,  and  over  the  areas,  indicated  in  the  following 
table: 


ROTHAMSTED   FIELD   EXPERIMENTS. 


CROPS. 

DURATION 
YEARS. 

AREA, 
ACRES. 

PLOTS. 

Wheat  (various  manures)  

41 

13 

37 

Wheat  alternated  with  fallow  
AVheat  (varieties) 

33 
15 

1 

4-8 

2 

About  20 

Barley  (various  manures)  
Oats  (,  various  manures)  
Beans  (various  manures) 

33 
101 
32  2 

! 

29 
6 
10 

Beans  (various  manures) 

273 

i 

5 

Beans  alternated  with  wheat      

28  4 

10 

Clover  (various  manures)          •             •  •  • 

30  5 

3 

18 

"Various  Leguminous  Plants 

7 

3 

17 

Turnips  ^  various  manures)  
Su^ar  Beet  (various  manures) 

28« 
5 

8 
8 

40 
41 

Mangel  Wurzel  (various  manures)  

9 

8 

41 

Total  Boot  Crops 

42 

Potatoes  (various  manures) 

9 

2 

10 

Rotation  (various  manures) 

37 

2V 

12 

Permanent  Grass  (various  manures)  .    ... 

29 

7 

22 

(x)  Including  1  year  fallow. 
(2)  1    "      wheat 


laiiow. 

wheat  and  5  years  fallow, 
i-;  4  years  fallow. 

(4)  "  2         "  " 

(5)  Clover,  12  times  sown,  8  yielding  crops,  but  4  of  them  very  small, 
1  year  wheat,  5  years  barley,  12  years  fallow. 

(6)  Including  barley  without  manure  3  years  (llth,  12th  and  13th  sea- 
sons.) 


Samples  of  all  the  experimental  crops  are  brought  to  the  laboratory. 
Weighed  portions  of  each  are  partially  dried  and  preserved  for  future 
reference  or  analysis.  Duplicate  weighed  portions  of  each  are  dried  at 
100°  C.,  the  dry  matter  determined,  and  then  burnt  to  ash.  The  quantities 
of  ash  are  determined  and  recorded,  the  ashes  themselves  being  pre- 
served for  reference  or  analysis.  In  a  large  proportion  of  the  samples 
the  total  nitrogen  is  determined,  and  in  some  the  amount  existing  as 
albuminoids,  amides,  and  nitric  acid.  In  selected  cases,  illustrating  the 
influence  of  season,  manures,  exhaustion,  etc.,  complete  ash-analyses 
have  been  made,  numbering  in  all  more  than  700.  Also  in  selected  cases, 
illustrating  the  influence  of  season  and  manuring,  quantities  of  the 
experimentally  grown  wheat-grain  have  been  sent  to  the  mill,  and  the  pro- 
portion and  composition  of  the  different  mill-products  has  been  deter- 
mined. In  the  sugar-beet,  mangel-wurzel,  turnips,  and  potatoes,  the 
sugar  in  the  juice  has,  in  many  cases,  been  determined,  by  polariscope, 
or  by  copper,  or  both.  In  the  case  of  the  experiments  on  the  mixed 
herbage  of  permanent  grass-land,  besides  the  samples  taken  for  the 
determination  of  the  chemical  composition  (dry  matter,  ash,  nitrogen, 
woody  fiber,  fatty  matter,  and  composition  of  ash),  carefully  averaged 
samples  have  frequently  been  taken  for  the  determination  of  the  botan- 
ical composition. 

Samples  of  the  soils  of  most  of  the  experimental  plots  have  been 
taken  from  time  to  time,  generally  to  the  depth  of  nine,  eighteen,  and 
twenty-seven  inches,  and  sometimes  even  to  four  times  this  depth.  In 
this  way  more  than  fifteen  hundred  samples  have  been  taken,  submitted 


to  partial  mechanical  separation,  and  portions  of  the  sifted  soil  have 
been  carefully  prepared  and  preserved  for  analysis.  In  a  large  proportion 
of  the  samples  the  loss  on  drying  at  different  temperatures,  and  at  igni- 
tion, has  been  determined.  In  most,  the  nitrogen  determinable  by  burn- 
ing with  soda-lime  has  been  estimated.  In  many,  the  carbon,  and  in  some 
the  nitrogen,  as  nitric  acid,  and  the  chlorine,  have  been  determined. 

Almost  from  the  commencement  of  the  experiments  the  rain-fall  has 
been  measured  ;  for  more  than  thirty  years  in  a  gauge  of  one-thousandth 
of  an  acre  area,  as  well  as  in  an  ordinary  small  funnel-gauge  of  five 
inches  diameter.  From  time  to  time  the  nitrogen  as  ammonia  (and 
sometimes  as  nitric  acid)  has  been  determined  in  the  rain-waters,  also 
chlorine  in  many  samples. 

Three  drain-gauges,  for  the  determination  of  the  quantity  and  compo- 
sition of  the  water  percolating,  respectively  through  twenty  inches,  forty 
inches,  and  sixty  inches  depth  of  soil  (with  its  subsoil  in  natural  state  of 
consolidation),  have  also  been  constructed.  Each  of  the  differently 
manured  plots  of  the  permanent  experimental  wheat-field  having  a 
separate  pipe-drain,  the  drainage  waters  have  been,  and  are  frequently, 
connected  and  analyzed. 

For  several  years  in  succession  experiments  were  made  to  determine 
the  amount  of  water  given  off  by  plants  during  their  growth.  In  this 
way  various  plants,  including  representatives  of  the  gramineous,  the 
leguminous,  and  other  families,  have  been  experimented  upon  ;  also  ever- 
green and  deciduous  trees. 

Experiments  upon  the  feeding  of  animals  were  commenced  in  1847, 
and  have  been  continued  at  intervals  up  to  the  present  time.  The 
following  points  have  been  investigated  : 

1.  The  amount  of  food,  and  its  several  constituents,  consumed  in  re- 
lation to  a  given  live-weight  of  animal  within  a  given  time. 

2.  The  amount  of  food,  and  of  its  several  constituents,  consumed  to 
produce  a  given  amount  of  increase  in  live-weight. 

3.  The  proportion,  and  relative  development,  of  the  different  organs 
or  parts  of  different  animals. 

4.  The  proximate  and  ultimate  composition  of  the  animals,  in  different 
conditions  as  to  age  and  fatness,  and  the  probable  composition  of  their 
increase  in  live-weight  during  the  fattening  process. 

5.  The  composition  of  the  solid  and  liquid  excreta  (the  manure)  in 
relation  to  that  of  the  food  consumed. 

6.  The  loss  or  expenditure  of  constituents  by  respiration  and  the  cuta- 
neous exhalations  —  that  is,  in  the  mere  sustenance  of  the  living  meat- 
and-manure-making  machine. 

Several  hundred  animals  —  oxen,  sheep,  and  pigs  —  have  been  sub- 
mitted to  experiment.  The  amount,  and  the  relative  development,  of 
the  different  organs  and  parts  were  determined  in  two  calves,  two  heifers, 
fourteen  bullocks,  one  lamb,  two  hundred  and  forty-nine  sheep,  and 
fifty-nine  pigs.  The  percentages  of  water,  mineral  matter,  fat,  and  nitrog- 
enous substances  were  determined  in  certain  separated  parts,  and  in 


TABLE  I. 

Wheat  grown  for  forty  years  in  succession  on  the  same  land,  Broadbalk 
Field,  Rothdmsted.  Results  showing  the  effects  of  exJiaustion,  and  of 
manure-residue.  Quantities  per  acre.  Produce — Dressed  Grain  in 
bushels. 

Mineral  Manure    " 

alone— blue; 
Ammonium  Salts 
alone  (86  Ibs.  Nitro- 
gen)— yellow; 
Min.  &  Amm.  Salts, 


Mixed 
Min.Manr 
Am.  Salts. 
172  Ibs.  N. 
13  years, 
1852-'64. 
Unman'd 
since. 


14  Tons 
Farm 
Yard 

Manure, 
every 
year. 


Mixed  Mineral 
Manure  alone, 

—  blue; 

Ammonium  Salts 
alone=86  Ibs.  Nitro- 
gen, —  yellow; 
alternately. 


Without!    Mixed 
Manure     Mineral 


—green; 
CTnmanured  — white 


Bushels 
20% 
32 
27  X 
29% 

S* 


Bushels.  Busnela. 


Harvests. 
1844 
1845 
1846 
1847 
1848 
1849 
1850 
1851 


8  yrs.  '44-'51 

1852 
1853 
1854 
1855 


1868 

1869 
1870 

1871 

1872 
1873 
1874 
1875 


1876 
1877 
1878 
1879 

1880 
1881 

1HS-J 


4  yrs.  '52-'55 
4  yrs.  '56-'59 
4  yrs.  '60-'63 
4  yrs.  '64-'67 
4  yrs.  '68-'71 
4  yrs.  '72-'75 
4  yrs.  '76-'79 
4  yrs.  '80-'83 

30% 
38 
37% 
34^ 
38% 
31% 
23 
34^ 

8  yrs.  '52-'59 
8  yrs.  '60-'67 
8  yrs.  '68-'75 
8  yrs.  '76-'83 

34% 
35% 
35% 
28% 

16  yrs.  '52-'67 
16yrs.'68-'83 

35% 
31% 

32yrs.'52-'83 

33% 

40yrs.'44-'83 

32% 

(1)  Average  of  5  years,  1860—1864,  inclusive. 
(3)  Average  of  5  years,  1860—1864,  inclusive. 
(5)  Average  of  13  years,  1852—1864,  inclusive. 


(2)  Average  of  3  years.  1865 — 1867,  inclusive. 
(4)  Average  of  11  years,  1865—1875,  inclusive. 
(6)  Average  of  19  years,  1865 — 1883,  inclusive. 


7 

the  entire  bodies,  of  ten  animals, —  namely,  one  calf,  two  oxen,  one  lamb, 
four  sheep,  and  two  pigs.  Complete  analyses  of  the  ashes,  respectively, 
of  the  entire  carcasses,  of  the  mixed  internal  and  other  "  offal "  parts,  and 
of  the  entire  bodies,  of  each  of  these  ten  animals,  have  also  been  made. 

From  the  data  provided  as  just  described,  as  to  the  chemical  compo- 
sition of  the  different  descriptions  of  animal,  in  different  conditions  as  to 
age  and  fatness,  the  composition  of  the  increase  whilst  fattening,  and  the 
relation  of  the  constituents  stored  up  in  increase  to  those  consumed  in 
food,  have  been  estimated.  To  ascertain  the  composition  of  the  ma- 
nure in  relation  to  that  of  the  food  consumed,  oxen,  sheep,  and  pigs 
have  been  experimented  upon.  The  loss  or  expenditure  of  constitu- 
ents, by  respiration  and  the  cutaneous  exhalations,  has  not  been  deter- 
mined directly,  but  only  by  difference, —  that  is,  by  calculation,  founded 
on  the  amounts  of  dry  matter,  ash,  nitrogen,  etc.,  in  the  food,  and  in  the 
(increase)  fceces,  and  urine. 

Independently  of  the  points  here  enumerated,  the  results  obtained 
have  supplied  data  for  the  consideration  of  the  following  questions  : 

1.  The  characteristic  demands  of  the  animal  body,  for  nitrogenous  or 
non-nitrogenous  constituents  of  food,  in  the  exercise  of  muscular  power. 

2.  The  sources  in  the  food  of  the  fat  produced  in  the  animal  body. 

3.  The  comparative  characters  of  animal  and  vegetable  food  in  human 
dietaries. 


Having  given  a  brief  outline  of  the  scope  and  plan  of  the  investiga- 
tions that  have  been  in  progress  at  Rothamsted  for  so  many  years,  I 
propose  to  draw  my  illustrations  as  to  the  character  and  significance  of 
the  results  obtained,  mainly  from  those  relating  to  the  growth  of  wheat 
for  more  than  forty  years  in  succession  on  the  same  land  : 

1.  Without  manure. 

2.  With  farm-yard  manure. 

3.  With  a  great  variety  of  chemical  manures,  both  individual  con- 
stituents and  mixtures. 

Table  I.  gives  the  number  of  bushels  of  dressed  grain  per  acre  without 
manure,  and  with  farm-yard  manure,  in  each  of  the  forty  years,  1844  to 
1883  inclusive;  and  on  some  of  the  artificially  manured  plots,  mainly 
selected  to  illustrate  the  effects  of  exhaustion  and  of  manure-residue.  In 
most  cases  in  this  table,  and  in  all  cases  in  the  subsequent  tables,  the 
results  obtained  on  the  artificially  manured  plots  are  only  given  for  the 
last  thirty-two  of  the  forty  years,  as  during  the  first  eight  years  the  ma- 
nures were  not  the  same  year  after  year  on  the  same  plot  as  they  were 
subsequently. 

FIRST.     WITHOUT  MANURE. 

After  a  five-course  rotation  since  manuring  (turnips,  barley,  peas, 
wheat,  oats),  the  first  experimental  wheat  crop  was  harvested  in  1844. 
The  highest  yield  of  the  series  was  23^  bushels  in  1845,  and  the  lowest 


8 

was  4^  bushels  in  1879.    Other  yields  have  been  21^  bushels  in  1854,  . 
20  in  1857,  only  5^  in  1853,  and  only  8-9  bushels  in  1867,  1875,  1876, 
and  1877. 

In  the  lower  division  of  the  table  (I.)  the  average  produce  is  given  for 
each  four  years,  each  eight  years,  each  sixteen  years,  and  for  the  thirty- 
two  years  from  1852  to  1883  inclusive;  also  for  the  whole  period  of 
forty  years.  Without  manure,  the  average  annual  produce  over  the 
four-year  periods  was  14^,  17^,  14^6,  12^,  13^,  10^,8^,  and  12^ 
bushels;  over  the  eight-year  periods,  16}^,  13^,  12^,  and  io}4  ',  over 
the  sixteen-year  periods,  14^5  and  u^j ;  over  the  thirty-two  years,  13^, 
and  over  the  forty  years,  14  bushels.  With  such  wide  variations  due  to 
season,  it  is  very  difficult  to  estimate  the  rate  of  decline  due  to  exhaus- 
tion. Excluding  the  very  bad  seasons,  the  decline  due  to  gradual  ex- 
haustion is  reckoned  at  from  one-fourth  to  one-third  of  a  bushel  per 
acre  per  annum. 

It  is  estimated  that  over  a  period  of  thirty  years  the  unmanured  plot 
yielded  an  average  of  18.6  Ibs.  of  nitrogen  per  acre  per  annum  in  the 
crop,  and  lost  a  minimum  of  10.3  Ibs.  in  drainage,  in  all  28.9  Ibs.;  whilst 
on  the  mixed  mineral  manure  plot  (5),  it  is  estimated  that  the  crop  re- 
moved an  average  of  20.3  Ibs.  of  nitrogen,  and  that  at  least  12  Ibs.  were 
lost  by  drainage,  or  in  total  32.3  Ibs.  Further  it  is  estimated  that  the 
soils  lost  to  the  depth  of  twenty-seven  inches  about  two-thirds  of  these 
amounts;  leaving,  say,  10  Ibs.  more  or  less  to  be  otherwise  accounted 
for.  Of  this,  the  rain,  etc.,  would  supply  5  Ibs.,  or  perhaps  rather  more, 
and  the  seed  about  2  Ibs.,  so  that  there  is  but  little  to  be  provided  from 
all  other  sources.  Lastly,  as  at  the  commencement  the  soil  was,  agri- 
culturally speaking,  exhausted,  the  nitrogen  supplied  by  it  would  be 
largely  due  to  old  accumulations. 

SECOND.     FARM-YARD  MANURE  EVERY  YEAR. 

In  the  application  of  farm-yard  manure  every  constituent  is  supplied 
in  excess.  The  highest  yields  of  the  series  of  years  were  44  bushels  in 
1863,41^  m  1868,41^  in  1857,  and  41^6  in  1854.  The  lowest  yields 
were  16  bushels  in  1879,  19^  in  1853,  20^  in  1844,  23^  in  1876,  and 
24^  in  1877. 

The  average  produce  per  acre  per  annum  over  each  of  the  five  eight- 
year  periods  was,  28,  34^,  35^,  35^,  and  28^  bushels.  Excluding 
the  first  eight  years,  and  several  of  the  recent  very  bad  seasons,  the 
average  produce  is  about  35  bushels  per  acre  per  annum. 

On  the  farm-yard  manure  plot,  the  first  nine  inches  of  soil  show  a 
great  accumulation ;  it  is  nearly  twice  as  rich  in  nitrogen  as  any  other 
plot,  yet  this  richness  is  not  proof  against  bad  seasons ;  nor  are  the 
highest  amounts  of  produce  in  the  field  obtained  on  this  plot. 

Thus,  without  manure,  or  with  mineral  manure  alone,  there  is  a  grad- 
ual decline  in  yield,  and  with  this  a  marked  reduction  in  the  nitrogen  of 
the  soil.  With  farm-yard  manure,  on  the  other  hand,  there  is  great  ac- 
cumulation, and  yet  not  the  fullest  crops,  a  large  proportion  of  the  con- 
stituents becoming  very  slowly  available. 

The  next  question  is,  which  constituents  of  farm-yard  manure  are  tht 
most  effective  for  wheat  in  this  agriculturally  exhausted  rather  heavy 
soil,  with  a  raw  clay  subsoil.  The  first  illustrations  on  this  point  will  be 
drawn  from  Table  II. 


TABLE  II. 

Wheat  grown  for  forty  years  in  succession  on  the  same  land, 

Broadbalk  Field,  Eothamsted;  commencing  1844. 

Results  showing  the  effects  of  different  manures  for  32  years,  1852-83  in- 
clusive.    Quantities  per  acre.    Produce — DRESSED  GRAIN  IN  BUSHELS. 


Superphosphate,  and  Sulphates  Potash,  Soda,  and  Magnesia. 


Alone. 

A  Amm.-salts  AAmm.-salts 
=43  Ibs.           =86  Ibs. 
Nitrogen.        Nitrogen. 

*  Amm.  -salts 
=129  Ibs. 
Nitrogen. 

*  Sodium  Ni- 
trate =86  Ibs. 
Nitrogen. 

Sodium  Ni- 
trate alone. 
=86  Ibs. 
Nitrogen. 

Plots. 

5 

6 

7 

8 

9a 

9b 

Harvests. 
1852 
1853 
1854 
1855 

Bushels. 
16f 
10J 
24| 
18J 

Bushels.   Bushels. 
201               26f 
18i               23f 
34£               45* 
28                 33~ 

Bushels. 
27i 
23* 
48| 
31 

Bushels. 
25£ 
ll{ 

38| 

Bushels. 

24i 

25| 

1856 
1857 
1858 
1859 

19* 
232 

181 
20f 

27} 
35 
28^ 
29^ 

36! 
44 
39) 
34 

39 
48 
41 
34 

32| 
43| 

157^ 
30 

26 
3& 
23 
24 

1860 
1861 
1862 
1863 

15i 
15* 
17! 
19 

\ 

22 
271 

28V 
39| 

27; 
35 
35i 

53: 

31 
351 
39 
55 

32f 
33| 
43* 

55| 

19 
131 

25T 

ft 

> 

1864 

1865 
1866 
1867 

167 
14] 
13 

9; 

31^ 
25 
20 
16 

, 

45^ 
40; 

2ft 

•2-2. 

49i 
43 
32 
30 

51i 
44 
32 
29, 

i 

33^ 
29^ 
30^ 
22^ 

1868 
1869 
1870 

1871 

t^  17  X  r-H 

TH  r-l  r-H  TH 

28| 
21 
30} 
17 

391 
28j 
40l 
223 

' 

46 
341 
45 

47] 
39 
45 
34i 
40J 
35i 
38 
30 

- 

27i 

24? 
26^ 
17| 

• 

1872 

1873 
1874 

is?:, 

CO  CO  tO  tO 

204 
15] 
25] 

29| 
22 
39 
25j 

35f 
27i 

40£ 
30 

2§i 

211 
21* 
16* 

1876 
1877 
1878 
1879 

10^ 
11 
14; 
5| 

15£ 
14| 

'2±\ 

m 

23 
19i 
31 

16; 

•29 
24| 
38 
20 

33j 
40 
37 
22 

13 

27f 
23f 
4| 

1880 
1881 
1882 
1883 

171 
12i 
12 
15^ 

27 
21f 
231 
27| 

344 
26 
35; 
36, 

- 

35* 
30; 
37 
41^ 

34 
35J 
31^ 
43 

10  i 
221 

AVERAGES. 


4  ys.  '52-55 
4  ys.  '56-59 
4  ys.  '60-63 
4  ys.  '64-67 
4  ys.  '68-71 
4  ys.  '72-75 
4  ys.  '76-79 
4  ys.  '80-83 

174 
20} 

17* 

13| 
16 
12 
10f 

14| 

251 

30* 

29f 
23J 

24f 
19| 

151 

32 
38 
38 
34J 
325 
29! 
22^ 
33; 

i 

1 

32J 
41 

40i 
39 
38^ 
33 

28; 
36; 

I 

\ 

26J 
36 
41 
39^ 
tt 
36 
33 
36 

t 

241 

27 
25; 
29 
23 
20! 
17 
19] 

! 

| 

8  ys.  '52-59 
8  ys.  '60-67 
8  ys.  '68-75 
8  ys.  '76-83 

19 
15J 
14 
12| 

271 
261 
22 
2pj 

35J 
36; 
31 

28 

t 

36J 
39i 
36 
323 

311 

40; 

39 
34| 

[ 

26J 

27^ 
22 
18; 

16  ys.  '52-67  , 
16  vs.  '68-83| 

171 
13k 

27 
211 

35i 

29J 

r 

38} 
34i 

r 

35| 
36^ 

L 

- 

26i 

20; 

32  ys.  '52-83J 

151 

24| 

32^ 

363 

363 

23J 

! 

Excess  of  ave- 
rage crop  over 
Plot  5  in  bush. 



Hi 

171 

• 

21 

21 

83 

IA 


10 


Taking  the  average  for  each  eight  or  sixteen  years  of  the  thirty-two, 
it  is  seen  that  in  every  case,  even  with  full  mineral  as  well  as  nitrogenous 
manure,  there  is  more  or  less  decline  in  the  later  periods  including  so 
many  bad  seasons;  excepting  on  ga,  where  the  nitrate  of  soda  is  always 
applied  in  the  spring.  The  low  results  or  great  decline,  on  gb,  where 
the  nitrate  is  used  alone,  show  the  want  of  minerals. 

The  average  of  the  thirty-two  years  of  mineral  manure  alone  shows 
an  increase  of  only  2*^  bushels  over  that  of  the  unmanured  plot,  though 
during  the  preceding  eight  years  it  had  been  manured,  whilst  the  unma- 
nured plot  had  already  grown  eight  unmanured  wheat  crops.  The  ad- 
dition to  the  mineral  manure  of  the  first  43  Ibs.  of  nitrogen  (plot  6)  gives 
an  average  annual  increase  of  8^  bushels,  the  second  43  Ibs.  (plot  7) 
an  increase  of  8^,  and  the  third  43  Ibs.  only  3^  bushels  increase.  This 
result  affords  an  illustration  of  the  inapplicability  of  conclusions  from 
manure  experiments,  when  the  condition  of  the  land  is  too  high  already, 
or  when  an  excess  of  manure  is  applied.  A  given  quantity  of  nitrogen 
in  the  form  of  nitrate,  yielded  more  produce  than  an  equal  quantity  in 
the  form  of  ammonia.  The  nitrate,  being  always  applied  in  the  spring, 
was  not  subject  to  winter  drainage.  It  is,  however,  very  soluble,  and 
becomes  rapidly  distributed  and  available ;  but  it  is,  at  the  same  time, 
very  subject  to  drainage  after  sowing,  if  heavy  rains  follow.  Prior  to 
1878,  the  ammonium-salts  were  applied  in  the  autumn,  and  a  great  loss 
of  nitrogen  by  winter  drainage,  chiefly  as  nitrates,  was  proved.  To  the 
loss  of  nitrogen  by  drainage  reference  will  be  made  further  on. 

Thus,  minerals  not  being  deficient,  the  increase  was  in  proportion  to 
the  available  nitrogen,  when  it  was  not  applied  in  excess. 

It  will  be  of  interest  here  to  call  attention  to  the  actual  amounts  of 
carbon  assimilated  per  acre  per  annum  in  wheat,  and  in  barley,  under 
different  conditions  of  manuring ;  also  to  the  increased  amount  assim- 
ilated under  the  influence  of  nitrogenous  manures. 

In  Table  III.  are  shown  the  estimated  amounts  of  carbon,  yielded  per 
acre  per  annum,  in  wheat  over  twenty  years,  and  in  barley  over  twenty 
years ;  each  with  the  complex  mineral  manure  alone,  and  each  with  the 
same  mineral  manure  and  given  quantities  of  nitrogen  in  addition, 
supplied  as  ammonium-salts,  or  as  nitrate.  The  gain  of  carbon  by  the 
use  of  the  nitrogenous  manure  is  also  given. 

TABLE  III. 

Yield  and  gain  of  Carbon  per  acre  per  annum  in  crops  at  Rothamsted. 

Average  Carbon  per 
acre  per  annum. 


Wheat  20  years—  1852,71. 

ACTUAL 
LBS. 

LBS. 
GAIN. 

Complex  Mineral  Mai 
do              do 
do              do 
do              do 

lure. 

988 
1590 
2222 
2500 

and  43  Ibs.  N.  as  Ammonia 
and  86  Ibs.  N.  as  Ammonia 
and  86  Ibs.  N.  as  Nitrate.  .  . 

602 
1234 
1512 

Barley  20  years— 1852,71. 


Complex  Mineral  Manure, 1138 

do  do        and  43  Ibs.  N.  as  Ammonia       2088  950 


It  is  quite  evident  that  in  the  case  of  these  gramineous  crops,  wheat 
and  barley,  which  contain  a  comparatively  low  percentage  of  nitrogen, 
and  assimilate  a  comparatively  small  amount  of  it  over  a  given  area, 
there  was  a  greatly  increased  amount  of  carbon  assimilated  by  the  addi- 
tion of  nitrogenous  manure  alone.  In  the  case  of  the  wheat,  there  was 
much  more  effect  from  a  given  amount  of  nitrogen  supplied  as  nitrate, 
which  was  always  applied  in  the  spring,  than  from  an  equal  quantity  as 
ammonium-salts,  which  were  applied  in  the  autumn  and  the  nitrogen  of 
which  was  subject  to  winter  drainage.  There  is  also  more  effect  from 
ammonium-salts  applied  to  barley  than  to  wheat ;  the  application  having 
been  made  for  the  former  in  the  spring  and  for  the  latter  in  the  autumn. 
It  should  be  observed  that  there  was  this  greatly  increased  assimilation  of 
carbon  in  the  wheat  and  in  the  barley  for  more  than  twenty  years,  with- 
out the  addition  of  any  carbon  to  the  soil.  It  is,  indeed,  certain  that, 
in  the  existing  condition  of  our  old  arable  soils,  the  increased  growth 
of  our  staple  starch-yielding  grains  is  greatly  dependent  on  a  supply  of 
nitrogen  within  the  "soil.  It'is  equally  certain  that  the  increased  pro- 
duction of  sugar  in  the  gramineous  sugar-cane,  in  the  tropics,  is  likewise 
greatly  dependent  on  the  supply  of  nitrogen  within  the  soil. 

It  will  further  be  of  interest  to  call  attention  to  the  connection  between 
nitrogen  accumulation,  chlorophyl  formation,  and  carbon  assimilation. 

TABLE  IV. 

Relation  of  Carbon  assimilation  to  Nitrogen  accumulation,  and  to  Chlo- 
rophyl formed. 


1 
Nitrogen 
percentage 
in  Dry 
Matter.* 

Relative 
Amount  of 
Chloro- 
phyl. 

Carbon  per  acre 
PIT  annum—  Ibs. 

Actual 

Difference. 

HAY. 

Graminese,  1.900 
Leguminosw,  2.478 

0.77 
2.40 





WHEAT. 

Plot  10a,  (1.227)              2.00 
Plot  7,  (0.566)              1.00 

1398 
2222 

-824 

BARLEY. 

Plot  la,  (1.474)              3.20 
Plot  4a,  (0.792)              1.46 

1403 

2088 

-685 

*  The  figures  given  in  parenthesis  are  on  the  substance  partially  dried,  but  not  fully  dried  at  100°  C. 

It  should  be  observed  that  the  amounts  of  chlorophyl  recorded  are 
as  stated,  relative,  and  not  actual ;  and  the  figures  show  the  relative 
amounts  for  the  individual  members  of  each  pair  of  experiments,  and  not 
the  comparative  amounts  as  between  one  set  of  experiments  and  another. 
It  should  further  be  stated  that  the  chlorophyl  determinations  were 
kindly  made  by  Dr.  W.  J.  Russell,  F.  R.  S.,  of  London,  in  specimens 
collected  at  Rothamsted,  whilst  the  wheat  and  barley  were  still  green, 
and  actively  growing. 

It  will  be  seen,  in  the  first  place,  that  the  separated  leguminous  herbage 
of  hay  contained  a  much  higher  percentage  of  nitrogen  in  its  dry  matter 
than  the  separated  gramineous  herbage  ;  and  that,  with  the  much  higher 
percentage  of  nitrogen  in  the  leguminous  herbage,  there  was  also  a  much 
higher  proportion  of  chlorophyl. 


12 


Next,  it  is  to  be  observed  that  the  wheat  plant  on  plot  loa,  manured 
with  ammonium-salts  alone,  shows  a  much  higher  percentage  of  nitrogen 
than  that  of  plot  7,  with  the  same  amount  of  ammonium-salts,  but  with 
mineral  manure  in  addition.  The  high  proportion  of  chlorophyl  again 
goes  with  the  high  nitrogen  percentage;  but  the  last  column  of  the  table 
shows  that  on  plot  loa,  with  ammonium-salts  without  mineral  manure, 
with  the  high  percentage  of  nitrogen  and  high  proportion  of  chlorophyl 
in  the  green  produce,  there  was  eventually  a  very  much  less  assimilation 
of  carbon.  The  result  is  exactly  similar  in  the  case  of  the  barley ; 
plot  i a  being  manured  with  ammonium-salts  alone,  and  plot  42.  with  the 
same  ammonium-salts  and  mineral  manure  in  addition. 

It  is  evident  that  the  chlorophyl  formation  has  a  close  connection 
with  the  amount  of  nitrogen  assimilated;  but  that  the  carbon  assimila- 
tion is  not  in  proportion  to  the  chlorophyl  formed,  if  there  is  not  a 
sufficiency  of  the  necessary  mineral  constituents  available.  No  doubt 
there  had  been  as  much  or  more  of  both  nitrogen  assimilated,  and 
chlorophyl  formed,  over  a  given  area,  where  the  mineral  as  well  as  the 
nitrogenous  manure  had  been  applied  ;  the  lower  proportion  of  both  in 
the  dry  matter  being  due  to  the  greater  assimilation  of  carbon,  and 
consequent  greater  formation  of  non-nitrogenous  substance. 

The  next  point  to  consider  is,  what  is  the  effect  of  the  unrecovered 
amount  of  nitrogen  on  succeeding  crops.  This  is  illustrated  Dy  the 
results  in  the  colored  columns  of  Table  I.  ,In  the  table  mineral  manure  is 
indicated  by  blue,  nitrogen  as  ammonium-salts  by  yellow,  and  a  mixture 
of  the  two  by  green.  Plot  5  has  been  manured  continuously  for  thirty- 
two  years  with  mineral  manure  alone;  whilst  plots  17  and  18  each 
received  mineral  manure,  and  a  quantity  of  ammonium-salts  containing 
86  Ibs.  of  nitrogen  alternately.  Thus  we  are  able,  for  every  year,  to 
compare  a  plot  manured  with  minerals,  succeeding  a  previous  applica- 
tion of  ammonium-salts,  with  a  plot  receiving  mineral  manure  alone 
yearly.  It  is  seen  that,  in  every  case,  the  application  of  nitrogen 
has  given  a  greatly  increased  yield,  frequently  doubling  that  of  the  plot 
with  mineral  manure  alone.  Again,  in  every  case,  the  yield  of  the  suc- 
ceeding year,  when  the  mineral  manure  was  applied,  was  reduced  ap- 
proximately to  that  of  the  plot  continuously  treated  with  minerals  alone. 
A  glance  down  the  alternately  blue  and  yellow  columns  of  plots  1 7  and 
1 8,  and  a  comparison  with  the  blue  column  of  plot  5,  will  bring  these 
results  strikingly  to  view.  A  comparison  of  the  averages  of  the  periods 
of  four,  eight,  sixteen,  and  thirty-two  years  of  this  treatment  clearly 
shows  the  essential  identity  of  the  results  of  the  continuous  and  the 
alternate  treatment  with  mineral  manures.  The  averages  for  the  thirty- 
two  years  show  an  increase  in  the  yield  of  the  mineral-manure  years 
after  ammonia,  over  the  yield  of  plot  5,  of  only  ^  of  a  bushel  per  acre 
per  annum  in  a  crop  of  between  fifteen  and  sixteen  bushels.  The  non- 
effect,  or  the  absence,  of  residual  nitrogen  applied  in  the  form  of  ammo- 
nium-salts, is  evident.  In  other  words,  nitrogen  as  ammonium-salts 
applied  in  any  one  year  is  practically  exhausted  that  year,  in  the  crop  or 
otherwise,  leaving  practically  none  for  subsequent  action. 

Again,  plot  16,  for  thirteen  years,  from  1852  to  1864  inclusive,  re- 
ceived annually  mixed  mineral  manure  and  ammonium-salts,  containing 
a  double  quantity  (172  Ibs.)  of  nitrogen ;  and  since  that  time,  for  nineteen 
years  (1864-1883),  it  has  been  left  unmanured.  During  the  thirteen 
years  of  heavy  manuring  there  was  a  large  yield,  in  two  cases  exceeding 


fifty  bushels,  with  an  average  for  the  thirteen  years  of  39^  bushels. 
The  first  three  years  during  which  no  manure  was  applied,  the  average 
yield  was  only  21^4  bushels,  a  decrease  of  nearly  one-half,  followed  in 
the  succeeding  periods  of  four  years  each  by  average  yields  of  17^,  12, 
9^5,  and  13^  bushels;  against,  for  the  corresponding  periods  on  plot  3, 
continuously  without  manure,  8^4,  13^,  10^,  and  12^  bushels.  Or, 
taking  the  average  of  the  nineteen  years  of  yield  without  manure  on  plot 
1 6,  we  have  14^5  bushels,  against,  over  the  same  years,  13^  bushels, 
on  plot  5,  with  mineral  manures  only,  since  1852,  and  nfo  bushels  on 
plot  3,  unmanured  since  1839.  It  is  fair  to  presume,  moreover,  that 
some  of  the  greater  yield  of  plot  16,  from  1864-1883,  over  that  of  plot 
3.  is  due  to  the  residue  of  the  mixed  mineral  manure,  which,  as  will  be 
seen  further  on,  has  some  effect  on  succeeding  crops. 

If,  as  the  above  results  have  demonstrated,  there  is  practically  no 
residue  from  previous  application  of  ammonium-salts,  the  question  arises, 
What  becomes  of  the  nitrogen  of  the  manure  not  taken  up  by  the  crop  ? 
This  point  is  illustrated  by  the  results  given  in  Table  V.  The  plots 
there  tabulated  all  received  the  same  amount  of  nitrogen  in  manure,  with 
differing  mineral  manures,  and  they  are  given  in  the  order  of  their  aver- 
age annual  increased  yield  of  nitrogen  in  the  crops  over  plot  5,  with 
mineral  manure  alone.  The  first  column  shows  the  estimated  average 
annual  increased  yield  of  nitrogen  per  acre  in  the  crops ;  the  second,  the 
estimated  annual  loss  of  nitrogen  as  nitric  acid  by  drainage ;  the  third, 
the  estimated  annual  excess  of  nitrogen  in  the  surface-soil  over  that  on 
plot  5  with  the  mineral  manure  alone;  and  the  last  column  shows  the 
relation  which  that  excess  in  the  soil  bears  to  100  increased  yield  of 
nitrogen  in  the  crops. 

The  plots  were  manured  as  follows: 

Plot  10  —  Amm. -salts  =  86  Ibs.  N. 

"  ii  — Amm. -salts  _  86  Ibs.  N.,  and  superphosphate. 

"  12  —  Amm. -salts  —  86  Ibs.  N.,  superphosphate  and  soda. 

"  13  —  Amm.-salts  =  86  Ibs.  N.,  superphosphate  and  potash. 

"  14  —  Amm. -salts  =  86  Ibs.  N.,  superphosphate  and  magnesia. 

"  7  —  Amm.-salts  =  86  Ibs.  N.,  and  mixed  mineral  manure. 

"  9  —  Nitrate  of  soda  =  86  Ibs.  N.,  and  mixed  mineral  manure. 


TABLE  V. 

BROADBALK  EXPERIMENTAL  WHEAT-FIELD. 

Estimated  Nitrogen  per  acre  per  annum. 


Plots. 

In  Crops  over 
Plot  5. 

Lost  by  Drain- 
age over  Plot  5. 

In  surface  soil  9 
inches  deep  over 
Plot  5. 

Excess  in  surface 
soil  to  100  increase 
in  Crop. 

Ibs. 

Ibs. 

Ibs. 

Ibs. 

10 

12.4 

31  2 

4.8 

38.7 

11 

17.7 

28.5 

11.6 

65.5 

12 

22.2 

24.5 

14.6 

65  8 

13 

23.4 

25.6 

17.8 

76.1 

14 

24  1 

27.5                     15  5 

64.3 

7 

25.9 

19.0 

19.3 

74  5 

9 

26.5 

23.7 

18.5 

71.2 

14 

It  is  seen  that  the  increased  yield  of  nitrogen  in  the  crops  varied  ex- 
ceedingly with  the  same  amount  supplied  in  manure,  according  to  the 
condition  as  to  supply  of  mineral  constituents.  Plot  10,  with  the  ammo- 
nium-salts alone,  gives  the  smallest  increased  yield  of  nitrogen  in  the 
crop ;  and  plots  7  and  9,  with  the  most  complete  mineral  manure,  each 
more  than  twice  as  much;  the  other  plots  giving  intermediate  amounts. 

The  order  of  the  estimated  loss  of  nitrogen  by  drainage  is  almost  the 
converse  of  that  of  the  increased  yield  in  the  crops.  Plot  10,  which 
gives  the  least  increased  yield  in  the  crop,  shows  the  greatest  loss  by 
drainage;  and  plots  7  and  9,  which  yield  the  greatest  increase  in  the 
crop,  show  the  least  loss  by  drainage. 

The  excess  in  the  soils  (over  plot  5)  is  obviously  much  more  in  the 
order  of  the  increased  yield  in  the  crops.  Plot  10,  with  the  least  in  the 
increase  of  crop  and  the  most  in  the  drainage,  shows  the  least  excess  in 
the  soil;  whilst  plots  7  and  9,  with  the  greatest  increased  yield  in. the 
crop,  and  the  least  loss  by  drainage,  show  the  greatest  excess  in  the  soil. 

It  is  clear,  therefore,  that  whilst  the  excess  in  the  soil  has  no  direct 
relation  to  the  amount  supplied  in  the  manure,  it  has  a  very  obvious 
relation  to  the  increased  yield  in  the  crop ;  in  other  words,  to  the  amount 
of  growth.  The  last  column  of  the  table  brings  this  out  more  clearly. 
Excepting  in  the  case  of  plot  10,  with  the  ammonium-salts  alone,  there 
is  a  general  uniformity  in  the  proportion  of  the  excess  in  the  soil  over 
plot  5  to  the  increased  yield  in  the  crop  over  plot  5 ;  and  the  variations, 
such  as  they  are,  have  an  obvious  connection  with  the  conditions  of 
growth.  Thus  plots  n,  12,  and  14,  all  with  a  deficient  supply  of  potash, 
show  approximately  equal  proportions  retained  in  the  soil  for  100  of  in- 
crease in  the  crop.  Plots  13,  7,  and  9,  again,  all  with  liberal  supplies  of 
potash,  show  higher,  but  approximately  equal,  proportions  retained  in 
the  surface-soil  for  TOO  of  increased  yield  in  the  crop. 

Upon  the  whole,  it  is  obvious  that  the  relative  excess  of  nitrogen  in 
the  soils  of  the  different  plots  is  little,  if  at  all,  due  to  the  direct  retention 
by  the  soil  of  the  nitrogen  of  the  manure,  but  it  is  almost  exclusively  de- 
pendent on  the  difference  in  amount  of  the  residue  of  the  crops  —  of  the 
stubble  and  roots,  and  perhaps  of  weeds. 

This  leads  to  the  consideration  of  the  actual  differences  in  the  crop 
with  equal  nitrogen  supply  and  different  mineral  supply.  This  is  illus- 
trated by  the  results  in  Table  VI.,  which  shows  the  effects  of  mineral 
manures  alone,  of  ammonium-salts  alone,  and  of  ammonium-salts  with 
different  mineral  manures. 


TABLE  VI. 

Wheat  grown  for  forty  years  in  succession  on  the  same  land. 
Broadbalk  Field,  Rothamsted. 

Results  showing  the  effects  of  Mineral  Manures  alone,  and  when  used 
in  addition  to  Ammonium-Salts. 

Quantities  per  acre.    Produce :  Dressed  Gi*ain  in  bushels. 


Mixed 
Mineral 
Manure 
Alone. 

400  Ibs.  Ammonium-Salts  =  86  Lbs.  Nitrogen  per  acre  per  annum. 

Alone, 
Alone,      1852  and 
1852  and      since.     !                                           And 
since,     j  Prev'sly                           And          Super- 
Previo'sly  Min.Man.   And  Su-       Super-    phosphate 
Min.Man.    1844,  '48    perphos-  phosphate       and 
1844.     j   and  '50.       phate.           and        Sulphate 
Am.-Salt>   Am.  -Su  its                      Sulphate          of 
1845-51.    1845/7,  '8,                       of  Soda.      Potash. 
'9  and  '.'.I. 

And 
Super- 
phosphate 
and 
Sulphate 
of 
Magnesia. 

And 
Super- 
phosph'te 
and 
Sulphates 
of  Potash, 
Soda 
and 
Magnesia. 

Plot  No—        Plot  5        Plot  lOa     Plot  lOb      Plot  11       Plot  12        Plot  l:i       Plot  14 

Plot  7 

Harvests. 
8  yrs.  '44/51 

Bushels. 
29 

Bushels.    Bushels.    Bushels.    Bushels,  i  Bushels.    Bushels. 
2»!                24%                                                   27%             -27', 

Bushels. 
29.%f 

1852 

1854 
1855 

1857 
1858 

I  S.V.I 

10% 

10 

34% 
20 

22% 
I''1, 
39% 

»H 

23% 

18% 
43% 
21% 

a*X 

22% 
45% 
31% 

24 
23 

-It': 

30% 

22% 
44% 
31% 
34% 
43% 
38% 
34% 

26% 
23% 
45% 
33 

23% 

18% 

24% 

-»'.»:... 
22% 
19 

27% 
34  % 
27% 
25% 

31  '4 
39% 
32 

27% 

33% 
43% 
37% 
34% 

31% 
43% 
37% 
34% 

36% 
44% 
39% 
34% 

I860 
1861 

1862 
1869 

1865 
1866 
1867 

1869 
1870 

1871 

1873 
1874 
1875 

15% 
15% 

17% 

14% 
13* 

9% 

15% 

12% 

g* 

24% 
43% 

22% 
24% 
26% 
45% 

27% 
32% 
33% 
54 

26% 
34% 
32% 

27  * 
33% 
31  %, 
54 

27% 
35 
35% 
,53% 

•_>r>  '  , 
18  K 

:»r,  -  , 
80% 
28% 

:{.;>, 

£* 

22% 

44% 
34% 
28% 

•24', 

4:*  '. 
37% 
24% 
23% 

41% 

8* 

22% 

45% 
40  % 
29% 
__23* 

17% 
15% 
18% 

•    24% 

-'I  ', 
10% 

T.'-K 

25% 
12% 

10 

18% 
20% 

14% 

Sg 

39% 
27% 
35% 
21% 

39% 
27% 
37 
30% 

41% 
27% 
35% 
24% 

39% 
28% 
40% 
22% 

12% 
13 
9% 

19* 

g 

29!* 

22% 
39% 
25% 

29% 
23% 

37% 
27% 

30% 

21   ':: 

36% 
26^ 

29% 
22 

39% 
25% 

1876 
1877 
1878 
1879 

10% 
11% 

14% 

5% 

ns 

14% 

29% 
4% 

14% 
17% 
29% 
11% 

19% 

17% 

14 

29% 
23% 
34% 
30% 

25% 
18  X 
29% 
16 

22% 
18% 
32% 
16% 

23% 
19% 
31% 
16  X 

isso 
1881 
1882 
1883 

17% 
12% 
1-2  >, 
15% 

10% 

18>4' 

23% 

17% 

13% 
19\ 

•_.,;,  ; 
18% 

25% 
21% 
30% 
26% 

33 

28  '4 
32% 
34% 

31 

27% 
34% 
33% 

34% 
26% 
35% 
36% 

4  yrs.  '52/55 
4  yrs.  '56/59 
4  yrs.  '60/63 
4  yrs.  '64/67 
4  yrs.  '68/71 
4  yrs.  '72/70 
4  yrs.  '76/79 
1  yrs.  '80/83 

17« 

20% 
17% 
13% 
16 
12 
10% 
14% 

23% 
22% 
25% 
It* 

18% 

15  'i 
17% 

26% 

28% 
2.V., 
25% 
20 
20% 
16% 
19% 

26% 
32% 

29% 
28.% 
23 
24% 

$* 

31  Ji 

37% 
37 
33 
30% 
29  \i 
20 
29% 

80* 

36% 
36% 
32% 
33% 
29% 
22  X 
31% 

30% 
37% 
36% 
32% 
32% 
29% 
22% 
31% 

32% 
38% 
38 
34% 
33% 
29% 
22% 
33% 

8  yrs.  '52/59 
8  yrs.  '60/67 
8  yrs.  '68/75 
8  yrs.  '76/83 

19 

14 

22% 
24 
19 

16% 

27% 
27'.! 
20% 
18% 

29% 
29% 
23% 

86 

30 

24% 

^ 
^ 

S 

y 

35% 
36% 
31 
28 

16  yrs.  '52/67 
16  yrs.  '68/83 

13% 

23% 

17% 

27% 

29% 
22% 

34% 
27% 

34 

2'J', 

34% 
28% 

35% 

29% 

32  yrs.  '52/83 

15>4 

20% 

23* 

26% 

31 

31% 

31% 

32% 

5 

lOa 

lOb 

11 

12 

13 

14 

7 

i6 

For  the  thirty-two  years, — 1852  to  1883  inclusive, —  each  of  the 
eight  differently  manured  plots  received  the  same  manure  each  year.  I 
will  only  call  special  attention  to  the  average  yields  over  periods  of  six- 
teen and  thirty-two  years. 

Plot  5,  treated  with  mineral  manure  only,  gave,  during  the  first  sixteen 
years,  an  average  yearly  yield  of  17^  bushels  per  acre,  during  the  second 
sixteen  years  13^  bushels,  and  during  the  whole  period  of  thirty-two 
years  15^  bushels. 

Plot  loa,  treated  with  ammonium-salts  only,  gave,  during  the  first 
sixteen  years,  an  average  yearly  yield  of  23^/6  bushels  per  acre,  during 
the  second  sixteen  years  17^  bushels,  and  during  the  thirty-two  years 
an  average  of  20^  bushels.  Thus,  ammonium-salts  alone  produced 
much  more  than  mineral  manure  alone. 

On  plot  lob,  previous  to  1852,  —  in  the  years  1844,  1848,  and 
1850, — mineral  manures  had  been  applied,  in  the  other  years  previous 
to  1852  (excepting  in  1846,  when  it  was  unmanured),  and  subse- 
quently, ammonium-salts  only.  The  effect  of  the  residue  of  the  pre- 
viously applied  mineral  manures  is  apparent  on  comparison  with  the 
yields  on  loa. 

On  plot  lob  we  find,  during  the  first  period  of  sixteen  years,  an 
average  yearly  yield  of  27^  bushels  per  acre,  against  23^  bushels  on 
loa;  during  the  second  period  of  sixteen  years  19^3  bushels,  against 
17^  on  ica;  and  during  the  thirty-two  years,  an  average  yearly  yield 
of  23 1^  bushels,  against  only  20^  on  loa. 

Plot  n,  with  superphosphate  but  no  potash,  in  addition  to  the 
ammonium-salts,  gave,  during  the  first  sixteen  years,  an  average  yearly 
yield  of  293/3  bushels  per  acre,  during  the  second  sixteen  years  22^ 
bushels,  and  during  the  thirty-two  years  26^  bushels. 

On  plot  12,  in  addition  to  the  ammonium-salts,  superphosphate  and 
sulphate  of  soda  were  applied ;  but  potash  had  been  applied  prior  to 
1852.  The  first  sixteen  years  produced  an  average  yearly  yield  of  34^ 
bushels  per  acre,  the  second  sixteen  years  of  27^  bushels,  and  the 
whole  thirty-two  years  of  31  bushels. 

On  plot  13,  the  ammonium-salts,  superphosphate,  and  sulphate  of 
potash  were  applied,  and  the  average  annual  produce  was,  over  the 
first  sixteen  years  34  bushels,  over  the  second  sixteen  years  29^,  and 
over  the  thirty-two  years  31^3  bushels. 

On.  plot  14,  besides  the  ammonium-salts  and  superphosphate,  sulphate 
of  magnesia  was  applied,  and  some  potash  had  been  applied  prior  to 
1852.  The  average  annual  produce  was,  over  the  first  sixteen  years 
34^  bushels,  over  the  second  sixteen  years  28^  bushels,  and  over  the 
thirty-two  years  3 1  ^  bushels. 

On  plot  7,  in  addition  to  the  ammonium-salts,  superphosphate  and 
the  sulphates  of  potash,  soda  and  magnesia,  were  applied,  and  gave, 
during  the  first  sixteen  years,  an  average  yearly  yield  of  35^  bushels 
per  acre,  during  the  second  sixteen  years  of  29^  bushels,  and  during  the 
whole  thirty-two  years  of  32^  bushels. 

Thus,  not  only  the  effect  upon  the  yield  of  wheat  of  a  direct  supply, 
but  of  a  residue  from  long  previous  applications  of  potash,  is  very  notice- 
able. This  is  rendered  more  obvious  by  reference  to  the  following  table 
(VII.),  in  which  the  pounds  per  acre  of  potash  and  phosphoric  acid 
removed  during  two  periods  of  ten  years  each,  in  the  total  produce, 


and  in  the  grain  alone,  of  the  plots  last  referred  to,  and  some  others 
are  given. 


TABLE  VII. 

Potash  and  Phosphoric  Acid  in  Grain,  and  in  Total  Produce. 
Ten  years,  1852-'61,  and  ten  years,  1862-71. 

PER  ACRE  IN   POUNDS. 


POTASH. 

PHOSPHORIC  ACID. 

1852-'61. 

1862-'71. 

1852-'61. 

1862-'71. 

TOTAL  GRAIN 

TOTAL  GRAIN 

TOTAL  GRAIN 

TOTAL  GRAIN 

PRODUCE. 

PRODUCE. 

PRODUCE. 

PRODUCE. 

2 

52.6 

11.8 

53.5 

12.4          26.5 

19.6 

27.3 

20.1 

3 

19.0 

5.5 

15.3 

4.9          10.8 

8.2 

9.7 

7.5 

5 

26.6 

6.6 

21.1 

5.7          14.7 

10.5 

12.3 

8.8 

lOa 

27.2 

7.1 

23.1 

7.7          13.0 

9.6 

13.4 

10.4 

lOh 

33.3 

8.5 

25.0 

87          16.0 

12.2 

14  8 

12.0 

11 

30.9 

9.3 

26  0 

8.8          19.8 

14.9 

18.0 

13.6 

12 

45.4 

11.4 

37.8 

11.4          23.2 

17  7 

21  8 

17.0 

13 

53.2 

11.3 

55.2 

12.2          22.9 

17  7 

23.3 

18.2 

14 

49.8 

11.3 

39.1 

11.6 

22.9 

17.9 

22.4 

17.6 

7 

56.0 

11.9 

53.0 

12.3 

23.8 

18.4 

23.4 

18  5 

I  will  illustrate  this  point  by  referring  only  to  the  potash.  Plots  3,  loa, 
lob,  and  n  show  a  deficiency  of  potash  in  both  grain  and  total  prod- 
uce compared  with  the  amounts  in  the  produce  of  plots  2, 12,  13, 14  and 
7,  on  all  of  which  there  was  a  sufficiency,  or  more  or  less  excess,  of 
potash  available.  On  comparison  of  these  results  with  the  manuring 
of  the  plots,  we  find  that  in  every  case  the  increase  of  potash  in  the 
total  crop  depends  either  on  a  direct  annual  potash  supply,  or  on  a 
residue  from  previous  applications.  The  first  ten  years  shows  more 
potash  in  the  total  produce  with  the  direct  supply  (13  and  7)  than  with 
the  residue  (12  and  14);  but  the  amount  in  the  grain  is  essentially 
the  same  in  each  case.  In  the  second  ten  years  there  is  a  greater 
difference  in  the  amounts  of  potash  in  the  total  produce  between  the 
plots  having  the  direct  and  those  having  only  the  residual  supply; 
whilst  there  is  scarcely  any  difference  in  the  amounts  in  the  grain,  but 
such  as  it  is,  it  is  in  accordance  with  the  conditions  of  supply.  Hence 
it  is  evident  that  whilst  the  plant  in  its  vegetative  stages  assimilates 
according  to  the  available  supply, — it  may  be  in  excess  of  actual  need, — 
if  there  is  no  deficiency,  the  composition  of  the  final  product — the 
seed — is  essentially  the  same. 

We  have  thus  traced  the  effects  of  exhaustion,  of  full  manuring,  and 
of  nitrogenous  and  non-nitrogenous  manures  on  one  particular  soil.  It 
has  been  seen  how  very  different  is  the  effect  of  one  and  the  same 
manuring  in  different  seasons,  but  the  real  extent  of  this  variation  is 
more  clearly  brought  out  in  Table  VIII.,  which  shows  the  best,  the  worst, 
and  the  average  produce,  over  a  period  of  thirty-two  years,  under  very 
opposite  conditions  as  to  manuring. 


i8 


TABLE  VIII. 

Wheat  year  after  year  on  the  same  land.    Broadbalk  Field,  Eothamsted. 

Produce  of  the  best  season,  1863 ;  the  worst  season,  1879 ;  and 
average  of  32  years,  1852-1883. 


Plot 
No. 

Description  of  Manures  —  Quantities  per  acre. 

Dressed  Grain  per  acre  —  Bushels. 

Best 
Season 

18(53 

Worst 
Season 
1879 

Diff. 

Average 
32  yrs. 
1852-'83 

3 
2 
5 
6 
7 
9 
8 

17* 

44 

19% 
39% 
53% 
55% 
55% 

4% 
16 
5% 

10% 

16^ 
22 

12* 

28 
14 

29% 
37% 
33% 
35^ 

13H 

33% 

15% 

24% 
32% 
36% 
36% 

Farm-yard  Manure 

Mixed  Min.  Man.  and  200  Ibs.  Amm.-Salts  =  431  bs.  Nit. 
Mixed  Min.  Man.  and  400  Ibs.  Amm.-Salts  =  861bs.Nit. 
Mixed  Min.  Man.  and  550  Ibs.  Nitra.  Soda  =  86  Ibs.  Nit. 
Mixed  Min.  Man.  and  600  Ibs.  Amm.  Salts=129  Ibs.  Nit. 

We  will  confine  our  attention  to  the  amount  of  dressed  grain  per  acre 
in  bushels.  The  difference  in  yield  of  the  various  plots  in  the  best  and 
worst  of  the  thirty-two  seasons  is  very  marked.  The  unmanured,  the 
mineral  manured,  and  the  heavily  nitrogeneous  manured  plots,  all  suf- 
fered severely.  In  most  cases  the  difference  approaches,  and  in  two 
cases  (Plots  6  and  7  mixed  mineral  manure,  together  with  200  and  400 
pounds  of  ammonium-salts,  respectively  furnishing  43  and  86  pounds  of 
nitrogen)  it  actually  exceeds  the  average  produce  of  the  plots.  From 
these  facts  we  see  how  easy  it  is  to  form  wrong  conclusions  as  to  the 
effects  of  different  manures,  if  experiments  are  conducted  in  only  one 
season  or  in  only  a  few  seasons,  and  if  the  characters  of  the  seasons  are 
not  studied. 

Not  only  season,  but  soil  and  locality  must  exercise  an  influence.  The 
Rothamsted  results  are  obtained  on  one  description  of  soil,  and  in  one 
locality  only.  Reference  to  the  following  table  (IX.)  shows  the  results 
obtained  in  experiments  conducted  at  Rothamsted  during  the  same 
eight  years,  but  in  two  fields;  at  the  same  place  in  one  field  for  thirty- 
two  years;  at  Woburn,  for  seven  years;  at  Holkham,  Norfolk,  for  three 
years;  and  at  Rodmersham,  Kent,  for  four  years.  Thus,  the  experi- 
ments were  made  on  very  various  soils,  under  various  conditions  from 
previous  treatment,  and  in  various  seasons,  yet  the  general  characters  of 
the  results  are  accordant. 

TABLE  IX. 

Results  of  Experiments  on  the  growth  of  Wheat  by  different  Manures, 
on  different  Soils,  in  different  Localities,  and  in  different  Seasons. 


DKESSED  GRAIN  PER  ACRE— BUSHELS. 

AVERAGE  ANNUAL  RESULTS. 


MANURES. 

QUANTITIES  PER  ACRE. 

Rothamsted. 

Woburn, 
Beds, 

7  years. 

Holkham,  Rodmers- 
Norfolk,   ham,  Kent 
3  years.      4  years. 

8  years  — 
1856-'63. 

32  years— 
1852-'83. 

Broadbalk 

Hoos 

Broadbalk 

1877-'83. 

1852-'54.      1856-'59. 

Field. 

Field. 

Field. 

I 

Unmanured  

16 

15 

18K 

15% 

18                 25% 

Mixed  Mineral  Mamire,  alone 

19 

16% 

16% 

16% 

19*             28% 

Amm.-Salts,  alone  =86  Ibs.  N. 

23% 

26% 

20% 

23%   1) 

27%             31% 

Mixed  Mineral  Manure,  and  ) 
Ammonium-Salts  =86  Ibs.N.  ) 

38% 

37% 

32% 

37%       |       32%             33% 

(1)    By  Ammonium-Salts  =  only  43  Ibs.  N. 


Not  only  is  there  general  accordance  in  the  character  of  the  results  in 
different  localities,  when  the  averages  of  a  number  of  years  are  taken, 
but  the  non-effect  of  the  residue  from  previous  application  of  ammonium- 
salts  is  as  marked  in  the  sandy  soil  at  Woburn  as  in  the  very  different 
soil  at  Rothamsted,  Reference  to  Table  X.  will  illustrate  this.  Stack- 
yard field.  Woburn,  received  mineral  manure,  and  ammonium-salts=:86 
Ibs.  nitrogen,  for  five  successive  years.  The  field  was  then  divided,  one 
portion  receiving  the  same  manure  as  before,  and  the  other  the  mixed 
mineral  manure,  but  no  nitrogen.  In  the  next  year,  1883,  the  portion 
which  had  received  nitrogen  in  the  previous  year  received  mineral  ma- 
nures only,  and  conversely  the  other  portion,  which  had  received  mineral 
manure  only  in  1882,  received  both  mineral  manure  and  ammonium- 
salts.  It  is  seen  that  in  each  year,  1882  and  1883,  the  portion  which 
received  the  nitrogenous  manure  yielded  large  crops  (43^  and  45^ 
bushels) ;  whereas,  the  portion  on  which  mineral  manures  alone  suc- 
ceeded ammonium-salts  and  large  crops,  yielded  very  small  crops  —  131^ 
and  171^  bushels,  respectively,  against  14^  and  17^  bushels  on  the 
plot  where  the  same  mineral  manures  were  used  year  after  year.  It  is 
thus  seen  that  there  was  no  available  and  effective  residue  where  the 
ammonium-salts  had  previously  been  applied.  It  may  be  stated,  how- 
ever, that  in  1884  there  was  notable  effect  from  unexhausted  residue  of 
nitrogenous  manure ;  the  explanation  probably  being  that  there  had  been 
very  little  rain,  and  consequently  very  little  loss  by  drainage  during  the 
winter  of  1883-4. 

TABLE  X. 

Wheat  grown  year  after  year  on  the  same  land. 
Stackyard  Field,  Woburn. 


Harvests. 

Dressed  Grain. 
Bueihels. 

1877 
1878 
1879 

g* 

28^ 

1881 
1882 
1883 

43% 
(1)  13^  1  (2)  43^ 
(2)  45%     (1)  17* 

(1)  Mixed  Mineral  Manure  alone.        (2)  Mix.  Min.  Man.  and  Ammonium-Salts  =  86  Ibs.  N. 

Having  illustrated  the  soil  conditions  necessary  for  the  growth  of 
wheat,  it  will  be  well  to  call  attention  to  one  practical  application  of 
these  long-continued  field  experiments.  For  thirty-two  years  (1852-83) 
an  estimate  has  been  made  of  the  average  produce  of  wheat  per  acre  in 
the  United  Kingdom,  based  upon  the  yield  at  Rothamsted  on  the  un- 
manured,  the  farm-yard  manured,  and  three  of  the  artificially  manured 
plots  taken  as  one.  From  this  the  total  yield  of  the  country  has  been 
calculated ;  to  this  the  imports  have  been  added,  and  the  quantity  re- 
quired for  seed  deducted,  the  final  figure  showing  the  total  amount 
available  for  consumption,  and  from  this  the  consumption  per  head  of 
the  population  has  been  reckoned.  It  may  be  said  at  once  that  these 
results  proved  to  be  very  near  the  truth.  But  the  point  of  interest  to  a 
wheat-growing  and  wheat-exporting  country  like  America  is,  the  evi- 
dence which  the  results  afford  as  to  the  constantly  increasing  require- 
ments of  a  largely  importing  country  like  Great  Britain. 


20 


The  following  table  (XI.)  shows  that  during  the  thirty-two  years, 
1852-3,  to  1883-4  inclusive,  the  area  under  wheat  in  the  United  King- 
dom has  been  reduced  by  about  one-third.  The  average  yield  per  acre 
is  estimated  at  28  bushels;  but  owing  to  recent  bad  seasons,  the  average 
for  the  whole  period  of  thirty-two  years  was  only  27  bushels,  that  for 
the  first  sixteen  years  having  been  28^,  but  that  for  the  second  sixteen 
years  only  25^.  Thus  there  has  not  only  been  a  reduction  in  area 
under  cultivation,  but  in  yield  per  acre,  also;  this,  however,  is  probably 
temporary,  whilst  the  reduction  in  area  will  doubtless  continue. 

TABLE  XI. 

Particulars  of  Home  Produce,  Imports,  and  Consumption  of  Wheat,  in 
the  United  Kingdom — 32  years,  1852-3  to  1883-4. 


Harvest 
years, 
Sept.  1  to 
Aug.  31. 

Estimated  Home  Produce. 

Available  for  consumption. 

Available  for  Con- 
sumption per  head. 

Area 
under 
Crop. 

Aver'g 
yield 
per 
Acre. 

Total 
Home 
Produce. 

Homepro-l 
duce  less 
2  ,14  bush's  Imports 
per  acre         less 
for  seed.  <  Exports. 

Total. 

From 
Home 
Pro- 
duce. 

From 
Im- 
ports. 

Total. 

1852-3 
1853-4 
1854-5 
1855-6 

Acres. 
.058.731 
.013.963 
.036.969 
.076.447 

Bushl.  Quarters. 
22%    11.574.982 
20%    10.466.473 
34%    17.563.140 
27%   13.922.801 

Quarters.  Quarters.    Quarters. 
1U.  433.  464   5.902.00016.335.464 
9.337.546   6.092.00015.429.546 
16.427.742   2.983.00019.410.742 
12.  776.300!  3.265.00016.041.300 

Bush. 
3.03 
2.70 
4.73 
3.65 

Bush. 
1.71 
1.76 
0.85 
0.93 

Bush. 

4.74 
4.46 
5.58 
4.58 

1856-7 
1857-8 
1858-9 
1859-60 

.213.651 
.185.974 
4.131.822 
4.019.725 

27      114.192.543 
33%  Il7.321.221 
31^    16.3U9.949 
26tf  J13.135.124 

13.007.453   4.112.58417.120.037 
16.143.915)  5.795.68721.939.602 
15.147.874  4.555.67019.703.544 
12.004.575  4.516.33216.520.907 

3.70 
4.56 
4.24 
3.34 

1.16 
1.63 
1.28 
1.25 

4.86 
6.19 
5.52 
4.59 

1860-1 
1861-2 
1862-3 
1863-4 

3.992.657 
3.898.177 
3.823.947 
3.698.629 

22%    11.078.948 
25  J£   12.271.546 
29^   13.957.554 
38%    17.922.048 

9  .  956  .  01210  .  023  .  968  19  .  979  .  980 
11.175.183   9.099.45520.274.638 
12.882.069   9.205.08622.087.155 
16.881.807   6.991.27023.873.077 

2.75 
3.06 
3.51 

4.57 

2.77 
2.49 
2.51 
1.89 

5.52 
5.55 
6.02 
6.46 

1864-5 
1865-6 
1866-7 
1867-8 

3.685.493 
3.646.691 
3.649.584 
3.628.910 

35  % 
30% 
25  % 
21 

16.216.328 
13.975.936 
11.485.091 
9.566.522 

15.179.783   5.500.70520.680.488 
12.950.305    7.313.02620.263.331 
10.458.645   7.633.03318.091.678 
8.545.890  9.015.54317.561.433 

4.08 
3.47 
2.78 
2.25 

1.48 
1.95 
2.02 
2.38 

5.56 
5.42 
4.80 
4.63 

1868-9 
1869-70 
1870-1 
1871-2 

3.937.275 
3.976.147 
3.761.457 

3.818.848 

34 

27 
30 
24 

16.733.419 
13.419.496 
14.105.464 
11.456.544 

15.626.060   7.719.30423.345.364 
12.301.205   9.921.52622.222.731 
13.047.554   8.008.83921.056.393 
10.382.493  9.316.60019.699.093 

4.09 
3.20 
3.33 
2.62 

2.02 
2.58 
2.05 
2.35 

6.11 

5.78 
5.38 
4.97 

1872-3 
1873-4 
1874-5 
1875-6 

3.827.146 
3.658.815 
3.821.655 
3.503.709 

24 

MX 

29^ 

22% 

11.481.438 
10.290.417 
13.972.926 
10.018.418 

10.  405.  053J12.  291.  463  22.  696.  516 
9  .  261  .  375  11  .  301  .  316  20  .  562  .  691 
12  .  898  .  085  11  .  705  .  255  24  .  603  .  340 
9.033.00013.860.07922.893.079 

2.60 
2.29 
3.16 
2.19 

3.07 

2.80 
2.87 
3.36 

5.67 
5.09 
6.03 
5.55 

1876-7 
1877-8 
1878-9 
1879-80 

3.114.555 

3.311.859 
3.372.590 
3.047.752 

25 

26% 
30 
15% 

9.732.984 
10.970.533 
12.647.213 
5.905.020 

8.857.01512.107.29420.964.309 
10.039.07314.408.62824.447.701 
11.698.67214.145.64925.844.321 
5  .  047  .  84016  .  409  .  933  21  .  457  .  773 

2.13 
2.38 
2.75 
1.17 

2.91 
3.42 
3.32 
3.82 

5.04 
5.80 
6.07 
4.99 

1880-1 
1881-2 
1882-3 
1883-4 

3.057.784 
2.960.066 
3.157.924 
2.707.949 

24% 
24 
25% 
28 

9.364.464 
8.880.198 
10.115.225 
9.477.822 

8  .  504  .  4621  16  .  182  .  210  24  .  686  .  672 
8.047.67917.200.10825.247.787 
9.227.059J19.982.16229.209.221 
8  .  616  .  211  15  .  815  .  878  24  .  432  .  089 

1.95 
1.83 
2.08 
1.92 

3.72 
3.91 
4.50 
3.53 

5.67 
5.74 
6.58 
5.45 

4  yrs.'52-'56 
4  yrs.'56-'60 
4  yrs.'60-'64 
4  yrs.'64-'68 
4  yrs.'68-'72 
4  yrs.'72-'76 
4  yrs.'76-'80 
4  yrs.'80-'84 

4.046.528 
4.137.793 
3.853.352 
3.652.670 
3.873.432 
3.702.831 
3.211.689 
2.970.931 

26%  il3.381.849 
29%  15.239.709 
28%  13.807.524 
28  12.810.969 
28%  |13.928.  731 
24%  11.440.800 
24  )i  9.813.938 
25%  9.459.427 

12.243.763  4.560.50016.804.263 
14.075.954j  4.745.06818.821.022 
12.723.768   8.829.94521.553.713 
11.783.656   7.365.57719.149.233 
12.839.328   8.741.56721.580.895 
10  .  399  .  378  12  .  289  .  528  22  .  688  .  906 
8  .  910  .  650  14  .  267  .  876  23  .  178  .  526 
8  .  598  .  85317  .  295  .  090,25  .  893  .  943 

3.53 
3.96 
3.47 
3.14 
3.31 
2.56 
2.11 
1.95 

1.31 
1.33 

2.42 
1.96 
2.25 
3.02 
3.37 
3.86 

4.  si 
5.29 
5.89 
5.10 
5.56 
5.58 
5.48 
5.81 

8  yrs.'52-'60 
8  yrs.'60-'68 
8  yrs.'68-'76 
8  yrs.'76-'84 

4.092.160 
3.753.011 
3.788.131 
3.091.310 

28  14.310.779 
28%  13.309.247 
26%  12.684.765 
24%  9.636.682 

13.159.859  4.652.78417.812.643 
12.253.712!  8.097.76120.351.473 
11.619.35310.515.54822.134.901 
8  .  754  .  75115  .  781  .  483(24  .  536  .  234 

3.74 
3.30 
2.94 
2.03 

1.32 
2.19 
2.63 
3.64 

5.06 
5.49 
5.57 
5.67 

16  yrs.'52-'68 
16  yrs.'68-'84 

3.922.586 
3.439.721 

2834'  13.810.013 
25%  11.160.724 

12  .  706  .  785!  6  .  375  .  273'19  .  J)82  .  058 
10.187.05213.148.51523.335.567 

3.53 

2.48 

1.75 
3.14 

5.28 
5.62 

32  yrs.'52-'84 

3.681.153 

27  112.485.369 

11.446.9191  9.761.894121.208.813 

3.00 

2.45 

5.45 

21 

The  great  increase  of  population  which  has  taken  place  within  the 
period  covered  by  the  table  has,  of  course,  necessitated  greatly  increased 
consumption,  and  the"  comparison  of  the  home  production  and  the  for- 
eign importation,  for  successive  periods,  becomes  of  much  interest.  The 
table  shows  that  the  average  annual  consumption  over  the  four  succes- 
sive periods  of  eight  years  each,  increase  as  follows  : 

1852-3  to  1859-60,  Annual  Consumption,  17,812,643  quarters. 

1860-1  to  1867-8,         "  20,351,473         " 

1868-9  to  1875-6,         "  "  22,134,901         " 

1875-6  to  1883-4,         «  24,536,234 

These  amounts  were  supplied  from  home  produce  and  importation  as 
follows: 

HOME  PRODUCTION.  IMPORTATION. 

1852-3  to  1859-60,  13,159,859  quarters.      4,652,784  quarters. 

1860-1  to  1867-8,  12,253,712         "  8,097,761         " 

1868-9  to  l875~6>  n»6i9>353        "  lo^S'S^        " 

1875-6  to  1883-4,        8,754,751  15,781,483 

Thus,  over  the  first  eight  years,  only  one-fourth  of  the  wheat  consumed 
was  obtained  from  foreign  sources,  whilst  over  the  last  eight  years,  nearly 
two-thirds  of  the  entire  consumption  were  imported.  It  is  probable  that 
the  home  produce  will  still  decline,  consequent  chiefly  on  reduction 
of  area  under  cultivation ;  whilst  with  increase  of  population,  imports 
must  increase,  and  doubtless  our  supplies  will  be  largely  drawn  from  this 
continent. 

It  has  been  stated  that,  excluding  recent  bad  seasons,  the  average 
yield  of  wheat  per  acre  of  the  old  arable  soils  of  Great  Britain,  is  twenty- 
eight  bushels.  Comparing  this  yield  with  that  of  the  United  States,  as 
shown  in  the  above  table,  we  find,  on  the  authority  of  the  U.  S.  Census 
Bureau,  that  the  general  average  of  localities  and  years  is  11.9  bushels 
per  acre ;  a  yield  which  is  not  equal  to  that  of  the  continuously  unma- 
nured  plot  at  Rothamsted,  and  which  is  considerably  less  than  half  the 
average  yield  of  Great  Britain  under  ordinary  cultivation.  This  may  be 
partly  due  to  a  shorter  period  of  growth,  and  to  rapid  maturing,  or  in 
some  localities  to  deficiency  of  rain ;  but  it  is  probably  largely  also  due 
to  want  of  sufficient  labor  to  clean  the  land,  and  to  consequent  luxuri- 
ance of  weeds. 

Referring  to  the  table,  we  find  the  general  averages  of  the  different 
sections  of  the  States  ranging  from  15.1  bushels  per  acre  in  New 
England,  to  7.3  bushels  in  the  South  Atlantic  and  Eastern  Gulf  States. 
Even  the  North-west  and  Minnesota,  including  much  prairie  land,  give 
very  meager  average  produce  for  such  rich  soil.  So  long  as  wheat  is 
grown  on  such  lands  under  the  conditions  frequent,  and  indeed  almost 
inevitable,  in  the  case  of  new  settlement, —  that  is,  growing  it  year  after 
year,  with  deficient  cultivation,  luxuriance  of  weeds,  and  the  burning  of 
the  straw, — only  low  yields  per  acre  can  be  expected.  The  result  is  due 
to  the  fact  that,  under  such  conditions,  fertility  is  cheap  and  labor  dear. 
But  with  increased  density  of  population,  more  mixed  agriculture  must 


22 

be  adopted.  Stock  must  be  kept,  the  farm  kept  freer  from  weeds,  the 
straw  used  instead  of  being  burnt,  and  the  manure  from  it,  and  from  the 
consumed  food,  returned  to  the  land.  Then,  and  not  till  then,  will  the 
fertility  of  the  rich  prairie  soils  be  conserved,  and  not  wasted,  as  is  too 
often  the  case  under  the  necessities  of  the  first  breaking  up,  and  the 
sparse  settlement,  of  the  country.  That  your  rich  prairie  soils  can,  and 
should,  yield  more  produce  than  they  do,  is  clear  from  the  high  yields 
obtained  occasionally,  under  favorable  conditions  of  cultivation. 

TABLE  XII 

Average  yield  per  acre  of  Wheat  and  Indian  Corn  in  the  United  States. 

(From  Signal  Service  Reports.) 
Six  years— 1875-1880. 

WHEAT— BUSHELS. 


1875 

1876 

1877 

1878 

1879 

1880 

Gl.Av. 

New  England,  

16.1 
10.6 
7.5 
9.0 
14.8 
9.5 
13.7 
7.5 
17.0 
11.0 

13.9 
12.3 
6.8 
6.7 
11.5 
10.5 
10.2 
9.5 
8.5 
13.0 

16.8 
13.2 
9.0 
7.2 
11.1 
12.8 
16.1 
14.8 
18.5 
9.5 

15.3 
14.0 
6.5 
7.1 
13.2 
13.0 
15.2 
12.2 
12.0 
17.0 

15.0 
13.4 
8.0 
8.1 
7.7 
16.3 
15.8 
13.1 
12.3 
14.0 

13.3 

14.!  5 
6.2 
5.6 
7.7 
14.1 
13.5 
12.5 
13.2 
16.0 

15.1 
13.0 
7.3 
7.3 
11.0 
12.7 
U.I 
11.6 
13.6 
13.4 

Middle  States 

South  Atlantic  States             

East  Gulf  States 

West  Gulf  States                             

Upper  Lake  Region,  

North  West  

Minnesota 

California    

Average,  

11.7 

10.3 

12.9 

12.6 

12.4 

11.7 

11.9 

INDIAN  COEN — BUSHELS. 


New  England,  

34.0 

35.8 

35.9 

36.5 

32.2 

32.9 

34  6 

Middle  States  

32.2 

29.2 

28.7 

28.7 

29.4 

32.9 

30.2 

•  South  Atlantic  States  

12.0 

11.5 

11.3 

11.4 

10.7 

10.2 

11.2 

East  Gulf  States 

15.0 

13  3 

132 

12  1 

14  3 

134 

13  6 

West  Gulf  States  

21.4 

23.2 

22.6 

24.2 

15.9 

24.0 

21.9 

Tennessee  and  Ohio  Valley,  

32.1 

31.4 

29.4 

29.2 

31.9 

29.7 

30.6 

Upper  Lake  Region  

27.0 

31.6 

23.3 

37.4 

38.1 

36.5 

32.3 

North  West 

35.7 

28  7 

31  2 

31  1 

36  2 

30  8 

32  3 

Minnesota    

29.2 

25.4 

29.0 

38.1 

35.0 

35.0 

32.0 

California 

363 

33  0 

30  0 

34  5 

280 

32  0 

32  3 

Average,  

27.5 

26.3 

25.5 

28.3 

27.2 

27.7 

27.1 

Turning  to  Indian  Corn,  Table  XII.  shows  that  the  yield  of  that 
cereal  is  very  much  higher  than  that  of  wheat ;  and  the  yield  of  nitrogen 
per  acre  in  those  corn  crops  would  doubtless  be  much  greater  than  in 
the  wheat  crops  of  the  same  localities.  This  is  probably  in  part  due  to 
the  high  condition  of  the  soil  under  which  the  crop  is  generally  grown, 
corn  generally  following  clover  in  the  rotation.  It  is,  however,  doubtless 
in  part  due  to  the  growth  of  corn  extending  much  further  into  the  late 
summer  and  autumn,  the  period  during  which  nitrification  is  the  most 
active  in  the  soil,  and  when  therefore  the  supply  of  nitrates  to  the  plant 
will  be  greater  under  the  same  conditions  of  soil  than  in  the  case  of 
wheat.  This  would  be  a  very  interesting  subject  for  investigation,  in 
the  field  and  in  the  laboratory,  tracing  the  nitrogen  at  various  periods  in 
the  soil,  in  the  plant,  and  in  the  drainage  waters. 

The  following  table  (XIII.)  gives  estimates  of  the  yield  of  various  crops 
on  some  Manitoba  prairie  soils  : 


23 

TABLE  XIII. 

Estimates  of  the  yield  of  various  Crops  in  Manitoba. 

Summary  of  Statistical  Eeturns — seven  years,  1876-1882. 
Quantities  in  bushels  per  acre. 


1876 

1877 

1878 

1879 

1880 

1881 

1882 

GEN'L 

AVER. 

Wheat, 
Barley, 
Oats, 
Bye, 
Peas, 
Potato*  s. 

32 

42 
51 

32 
229 

27 
41 
60 
30 
32 
304 

26 
36 
60 
30 
34 
308 

27 
38 
58 
40 
32 
302 

29 
41 
58 
40 
38 
318 

30 
40 
59 
35 
38 
320 

32 
37 
51 

278 

29 
39 
57 
35 
34 
294 

The  above  estimates  are  founded  on  the  reports  of  numerous  farmers, 
and  it  is  seen  that  the  average  yield  of  wheat  for  seven  years  (1876- 
1882)  is  assumed  to  be  twenty-nine  bushels.  This  is,  however,  doubtless 
too  high,  even  for  exclusively  virgin  prairie  soils,  under  the  condition 
of  cultivation  incident  to  new  settlement ;  and  the  result  is  probably 
accounted  for  by  the  fact  that  the  records  come  chiefly  from  the  more 
intelligent  and  better  farmers.  From  returns  since  supplied  to  me 
from  the  Department  of  Agriculture  at  Ottawa,  the  average  produce  of 
wheat  in  Manitoba  was,  in  1880,  20.1  bushels,  and  in  1882,  24.0  bushels, 
instead  of  29  and  32  bushels  as  above;  whilst  the  average  produce  in 
1883  is  estimated  at  21.8  bushels. 

In  connection  with  this  subject  of  the  average  yield  of  wheat  of  differ- 
ent countries,  it  will  be  of  interest  to  contrast  the  condition  of  soils  of 
very  different  history,  as  to  their  percentage  of  nitrogen,  and,  so  far  as 
we  are  able,  of  carbon  also. 

Table  XIV.  (see  next  page)  shows  the  characters  in  these  respects  of 
exhausted,  arable  soils,  of  newly  laid  down  pasture,  and  of  old  pasture 
soils,  at  Rothamsted;  of  some  other  old  arable  soils;  of  some  Illinois 
and  Manitoba  prairie  soils;  and  lastly,  of  some  very  rich  Russian 
soils. 

From  these  results  there  can  be  no  doubt  that  a  characteristic  of  a  rich 
virgin  soil,  or  of  a  permanent  'pasture  surface-soil,  is  a  relatively  high 
percentage  of  nitrogen  and  of  carbon,  and  a  high  relation  of  carbon  to  ni- 
trogen. On  the  other  hand,  a  soil  that  has  long  been  under  arable  culture 
is  much  poorer  in  these  respects ;  whilst  an  arable  soil  under  conditions 
of  known  agricultural  exhaustion  shows  a  very  low  percentage  of  nitro- 
gen and  of  carbon,  and  a  low  relation  of  carbon  to  nitrogen. 

Finally,  it  has  been  maintained  by  some  that  a  soil  is  a  laboratory, 
and  not  a  mine.  But  not  only  the  facts  ascertained  in  our  own  and  in 
other  investigations,  but  the  history  of  agriculture  throughout  the  world, 
so  far  as  we  know  it,  clearly  show  that  a  fertile  soil  is  one  which  has 
accumulated  within  it  the  residue  of  ages  of  previous  vegetation,  and 
that  it  becomes  infertile  as  this  residue  is  exhausted ;  and  enormous  as  are 
the  accumulations  in  the  prairie  lands  of  the  American  continent,  it  is 
still  desirable  to  postpone,  rather  than  to  accelerate,  the  time  of  their 
exhaustion. 


TABLE  XIV. 

Nitrogen  and  Carbon  in  various  soils. 


Date  of  Soil 
Sampling. 

(1)  In  Dry  Sifted 
Soil. 

Authority. 

Nitrogen. 

Carbon. 

Carbon 
to  1 
Nitrogen. 

ROTHAMSTED  ARABLE  AND  GRASS  SOILS. 


Roots,    1843-'52  ;      Barley,    1853-'5  ;  > 
Roots,  1856-'69  ;  Mineral  Manures.  5 
Wheat,  1843-'4,  and  each  year  since  ;  / 
Mineral  Manures  £ 
Barley,  1852,  and  each  year  since  ;  } 
Mineral  Manures  <, 
Arable   laid   down    to  grass   (ten  > 
acres),  Spring,  1879  \ 
Arable  laid  down  to  grass  (Barn-  > 
field),  Spring,  1874  \ 
Arable  laid  down  to  grass  (Apple-  ? 
tree  field),  Spring,  1863                    J 

April,  1870 

Per 
cent. 

0.0934 

0.1119 
0.1012 
0.1202 
0.1124 

0.1235 
0.1509 
0.1740 
0.2057 

0.1943 
0.2466 

Per 

cent. 

1.039 
1.079 

Per 

cent. 

9.3 
10.7 

Rothamsted. 

« 

H 

« 

October,  1865  
October,  1881  .  . 
March,  1868  
March,  1882  

February,  1882.. 
February,  1882.. 
November,  1881  . 

1.154 

2.412 

2.403 
3.377 

10.3 

11.7 

12.4 
13.7 

Arable  laid  down  to  grass  (Dr.  Gil-  ?  To 
bert's  meadow),  Spring,  1858  5  January,  1879  .  .  . 
Arable  laid  down  to  grass  (High-  )  L     -      , 
field),  Spring  (?),  1838   .......$  September,  1878. 
Very  old  grass  land  (The  Park)  Feb.  &  Mch.,  1876 

VARIOUS  ARABLE  SOILS  IN  GREAT  BRITAIN. 


Mr.    Prout's   Farm  ;    Broadfield  —  ) 
surface  $ 
Mr.    Prout's    Farm;    Blackacre  —  > 

0  170 
0.107 

Voelcker. 

Mr.  Prout's    Farm;   Whitemoor  —  > 
surface                                              5 

0.171 

« 

Wheat  Soil  —  Midlothian  .  . 
Eastlothian  

0.22 
0.13 

Anderson. 

Perthshire 

0  21 

(t 

"            Berwickshire 

0  14 

tt 

Red  Sandstone  Soil  —  England  

0.18 

.... 

Voelcker. 

UNITED  STATES 

AND  CANADIAN  P 

RAIRIE 

SOILS. 

Illinois,  U.  S.,  No.  1... 

0  30 

"           "      No  2 

0  26 

.... 

"           "      No.  3. 

0  33 

l( 

"           "      No.  4  

0  34 

tt 

Portage  la  Prairie,  Manitoba  —  sur-  > 
face                                                   5 

0.247 

Rothamsted. 

Saskatchewan  district,  N.  W.  Terri-  > 
tory  —  surface  5 
Forty  miles  from  Fort  Ellis,  N.  W.  > 

0.303 
0  250 

.... 

.... 

" 

Territory  —  surface  3 

Niverville,  Manitoba  —  1st  12  inches. 
Brandon,           "                       " 
Selkirk,             "                      " 
Winnipeg,         " 

0.261 
0.187 
0.618 
0.428 

3.42 
2.66 
7.58 
5.21 

13.1 
14.2 
12.3 
12.2 

Rothamsted. 

I 

tUSSIAN  SOILS. 

No.  1  —  12  inches  

0  607 

C  Schmidt 

No.  2—8 

0  467 

No.  3—5                

0  188 

44 

No.  4—  6                

0  130 

H 

No.  5—  11 

0  305 

(( 

No.  6—  17                

0  281 

II 

No.  7—9         ' 

0  409 

II 

(1)  Calculated  on  soil  dried  at  100  C. 


YC  20929 


D 

OQ 


ITY  OF  CALIFORNIA  LIBRARY 


